Ski lubricant comprising paraffinic wax and a hydrocarbon compound containing a perfluoro segment

ABSTRACT

Compounds which can be defined by the formula (I): 
     
         CF.sub.3 --C.sub.n F.sub.2n --C.sub.m H.sub.2m --CH.sub.3  (I) 
    
     wherein: 
     n is a numeral comprised within the range of from 1 to 21; 
     m is a numeral comprised within the range of from 3 to 25; 
     n+m is a numeral equal to, or higher than, 18; 
     with the chain of carbon atoms being either linear or branched 
     are used as agents affording sliding characteristics (ski-waxes) for skis, to be applied onto the ski sole, and/or to be incorporated inside the ski sole. A sliding composition is also disclosed, which contains a paraffinic wax and at least one compound with formula (I).

The present invention relates to agents affording slidingcharacteristics and to their use to afford sliding characteristics toskis.

In the art the use is known of ski-waxes to improve the slidingcharacteristics of skis. These ski-waxes normally contain suchsubstances as animal oils, vegetable oils, paraffinic waxes, fattyalcohols, esters of fatty alcohols and still other chemicals, usually asmore or less complex mixtures.

In the art, also agents of non-traditional type to afford slidingcharacteristics to skis have been disclosed, which agents are endowedwith improved characteristics compared to conventional ski-waxes. Inparticular, European Patent Application Publication No. 132,879discloses a solid agent for affording sliding characteristics to skis,which is essentially constituted by linear perfluoroparaffins containingfrom 10 to 20 carbon atoms in their molecule, which can be used also asmixtures with paraffinic waxes and in general with conventionalski-waxes. The drawback which affects these sliding agents basicallyconsists in their poor compatibility with paraffinic waxes, so that ingeneral a compatibilizer agent must be used, in particular a fluorinatedsurfactant.

The present Applicant has found now that some organic compoundsconsisting of a paraffinic hydrocarbonaceous segment and aperfluorinated paraffinic hydrocarbonaceous segment chemically linked toeach other, constituted extremely good sliding agents for skis. Inparticular, the present Applicant was able to find that a such a slidingeffect manifests itself both whether the compounds are applied to theski sole, or if they are incorporated inside said ski sole, during astep of the ski manufacturing process. The present Applicant has alsofound that these compounds consisting of two segments are compatiblewith the conventional ski-waxes and that they can be mixed with thelatter without the aid of any compatibilizer agents, to yieldcomposition which make it possible improved performances to be obtainedin the ski sector.

In accordance therewith, according to an aspect thereof, the presentinvention relates to a compound or mixture of compounds with formula(I):

    CF3--CnF2n--CmH2m--CH3                                     (I)

wherein:

n is a numeral comprised within the range of from 1 to 21;

m is a numeral comprised within the range of from 3 to 25;

n+m is a numeral equal to, or higher than, 18;

with the chain of carbon atoms being an either linear or branched chain;

to be used as an agent to afford sliding characteristics (i.e., as aski-wax) to skis.

According to a preferred form of practical embodiment of the presentinvention in formula (I):

n is a numeral comprised within the range of from 3 to 15;

m is a numeral comprised within the range of from 5 to 23;

and

n+m is a numeral equal to or higher than 18;

with the chain of carbon atoms being an either linear or substantiallylinear chain.

According to the present invention by "linear or substantially linear"with regard to the chains of carbon atoms of compounds with formula (I),it is herein meant that said chains are linear for at least 90%, up to100%.

Examples of specific compounds with formula (I) are:

CF3--(CF2)5--(CH2)15--CH3--a semi-solid, colourless product with waxyappearance, with melting point 31°-32° C.;

CF3--(CF2)7--(CH2)15--CH3--a solid, colourless product with waxyappearance, with melting point 49°-51° C.;

CF3--(CF2)7--(CH2)19-13 CH3--a solid, colourless product with waxyappearance, with melting point 68°-72° C.;

CF3--(CF2)7--(CH2)p--CH3--a solid, colourless product with waxyappearance, which is a mixture of four components with p=17, 19, 21 and23, with melting point 59°-62° C.

The compounds with formula (I) can be prepared by methods known in theart and disclosed, e.g., in U.S. Pat. No. 3,145,222 and J. Org. Chem.34, 2441 (1969) and 40, 851 (1975).

The preferred process to prepare the compounds with formula (I)comprises:

(a) a reaction of addition of a 1-perfluoroalkyl iodide and analpha-olefin, in the presence of a free-radical catalyst, according tothe following reaction scheme:

    CF3--(CF2)n-1--CF2--I+CH3--(CH2)m-2--CH═CH2→→CF3--(CF2)n-1--CF2--CH2--CHI--(CH2)m-2--CH3

(b) a reaction of reduction of the product of reaction from the (a)step, carried out with zinc powder in the presence of aqueoushydrochloric acid, according to the following reaction scheme:

    CH3--(CF2)n-1--CF2--CH2--CHI--(CH2)m-2--CH3+Zn+HCL→→CF3--(CF2)n-1--CF2--CH2--CH2--(CH2)m-2--CH3

More particularly, the addition reaction (a) is carried out in theabsence of solvents or diluents, with an excess of at least 50% ofeither of the reactants. The free-radical catalyst is a catalyst capableof forming free radicals under the conditions under which the reactionis carried out.

For that purpose, azo-compounds are advantageously used, such asazo-bis-isobutyronitrile, or peroxides, such as benzoyl peroxide and3-tert.butyl-peroxyethylhexanoate. The reaction temperature is generallycomprised within the range of from 60° to 100° C., and is anywayselected as a function of the particular free-radical initiator and ofthe relevant decomposition kinetics. At reaction end, the excess ofreactant is removed by evaporation under reduced pressure. By operatingunder the above conditions, yields and selectivities to the usefulreaction product higher than about 95% are usually accomplished.

In the step (b), the reduction reaction is carried out by adding to thereaction mixture coming from the (a) step, a solvent and generally alow-boiling aliphatic alcohol (e.g. ethanol), zinc powder and thenaqueous hydrochloric acid, for example hydrochloric acid at aconcentration comprised within the range of from 10 to 37% by weight.Zinc and hydrochloric acid are added in an excess of at least 100%relatively to the stoichiometric amount required for the reduction.Under these conditions, the yield of the reduction reaction is higherthan approximately 99%. At the end of the reaction, the reaction mixtureis diluted with a solvent (e.g., toluene) and water, so as to allow agood separation of the aqueous and organic phases to take place. Thereaction mixture should advantageously be kept at temperatures higherthan room temperatures, so as to prevent the reaction product containedin the organic phase from solidifying. The excess of zinc is filteredoff. The organic phase is separated from the aqueous phase, the solventis evaporated off under reduced pressure and the desired reactionproducts is recovered.

According to the present invention, the compounds or mixtures ofcompounds (I) are used as agents affording sliding characteristics(ski-waxes) to skis, by application onto the ski sole, in particular apolyethylene sole. For example, the application may be carried out bymelting the compounds (I) on the spot with a hot iron, followed by aleveling by means of a blade and brushing. The function of so appliedcompounds (I) is of reducing to a considerable extent the surfacetension of the ski sole, increasing the water-repellancy thereof, andallowing skis to slide more easily on the water film which is formed,due to pressure and friction phenomena, at the interface between thetheir sole and the underlying snow.

According to another form of practical embodiment of the presentinvention, the compounds (I) are incorporated inside the ski sole. Skisoles are normally made from high-density polyethylene, They tipicallyshow a thickness of from 1.2 to 1.4 mm and are manufactured by processesof polymer extrusion or of polymer powder sintering. In case ofextrusion, a polyethylene is normally used which has an averagemolecular weight of the order of 400,000-800,000, and the extrusion iscarried out at temperatures of the order of from 220° to 240° C. Apolyethylene useful for that purpose is the product available from BASFcompany under the trade name "Lupolen 5661B". The so manufactured skisoles are normally intended for use on the skis for non-competitivesector. In case of manufacture by sintering, a polyethylene having ahigh average molecular weight (of the order of from 3 to 5 millions) isused. A polyethylene useful for that purpose is the product availablefrom Hoechst company as "Hostalen-Gur-412". The process consists insintering the polymer powder at temperatures of from 250° to 300° C.,under pressures of from 150 to 200 kg/cm², for times of the order offrom 12 to 24 hours, inside moulds with cylindrical shape, whose heightequates the width of the ski sole. The resulting polyethylene cylinderis laminated along its circumference. The so manufactured ski soles areintended for use in the competitive sector. In order to accomplish animprovement in the sliding characteristics of the so obtained ski soles,the compounds (I), and in particular those with a higher molecularweight, non-volatile or at least poorly volatile under processingconditions, are mixed with the polymer powder and the so obtainedmixture is submitted to the extrusion or sintering treatments asdisclosed above. In particular, the amount of compounds (I) admixed withthe polymer powder may be comprised within the range of from 0.5 to 10%by weight, and preferably of from 2 to 8% by weight, relatively to theweight of the sole. The so obtained soles show a decrease in theirsurface tension, evidenced by a significant increase in the contactangle, compared to the soles manufactured from the same polyethylene inthe absence of the compounds of formula (I). This decrease in surfacetension is thought to derive from the fact that the perfluorinated chainof the compounds (I) tend to position itself towards the outside on thelimit surface, orientating itself, in such a way as to generate a "brusheffect".

Of source, the application of compounds (I) inside the sole and onto thesole of a same ski falls within the scope of the present invention.

Therefore, according to another aspect thereof, the present inventionrelates to a ski characterized in that it bears on its sole and/orincorporated inside its sole, at least one compound of formula (I).

According to yet another aspect, the present invention relates to acomposition (mixture) affording sliding characteristics, whichcomprises:

a paraffinic wax, and

a compound or mixture of compounds with formula (I), as defined above.

By the term "paraffinic wax" according to the present invention thoseproducts known from the prior art are meant which are usually spread onthe ski sole in order to increase the sliding characteristics thereofand which, besides to waxes or paraffinic compounds in general, maycontain one or more from animal or vegetable oils, fatty alcohols andesters of fatty alcohols, fatty acids and esters, fatty acids amides andsalts, or any other ingredients conventionally used for that purpose,such as, e.g., siliconic compounds, Teflon powder and graphite powder.In particular, within the scope of this definition the conventionalski-waxes fall, which incorporate one or more of the above reportedcompounds, and which are easily available on the market.

In the composition affording sliding characteristics according to thepresent invention, the content of compound or mixture of compounds withformula (I) may be generally comprised within the range of from 0.1 to99% by weight and preferably of from 3 to 25% by weight, relatively tothe weight of the composition.

In particular, the present Applicant was able to find that the compoundsof formula (I) can be mixed and homogenized with a paraffinic wax, ornormally with a conventional ski-wax available from the market, bymelting the ingredients, with no need to use compatibilizer agents. Themixture and homogenizing of compounds of formula (I) into a paraffinicwax or into a conventional ski-wax can be obtained as well by dissolvingat high temperature the ingredients in a suitable solvent, for examplewhite spirit, or in an aliphatic solvent based on octane or decane,followed by partial or total co-precipitation at low temperature of thesolid ingredients in dispersed form. In this case a more or less thickpaste is obtained which is easily applied to the ski sole, for exampleby a cloth. The treatment with the leveling blade and the brushing arecarried out after the evaporation of the solvent. In any case thenon-fluorinated paraffinic portion of compounds (I) allows thedissolving effect into the commercial ski-waxes, which generally show ahigh affinity for such a paraffinic portion, to take place. Furthermore,when such a composition or mixture is applied to the sole of a ski, thefluorinated paraffinic portion of compounds (I) tends to position itselfat the limit surface, with a "brush effect", lowering the surfacetension thereof, as demonstrated by significant increase in contactangle, as compared to conventional ski-waxes.

Therefore, the introduction of the compounds of formula (I) into theconventional ski-waxes enhances the sliding effect thereof. Such animprovement can be observed under all conditions of snow temperature andair humidity, and is optimum with snow temperatures comprised within therange of from 0° to -15° C., and with a relative humidity of atmosphericair comprised within the range of from 40 to 100%. The extent of suchimprovements, evaluated on snow-covered fields, on stretches with alength of the order of 150 meters and with slopes of the order of 20%,is such as to allow a reduction of up to about 3% in descent time to beaccomplished.

Therefore, according to a further aspect thereof, the present inventionrelates to a ski characterized in that it bears on its sole the slidingcomposition as defined above, and which may additionally contain atleast one compound of formula (I) incorporated inside its sole.

The following experimental examples are reported to better illustratethe present invention.

EXAMPLE 1

Preparation of CF3--(CF2)7--(CH2)19--CH3 (Molecular weight 700).

The following are charged to a three-necked flask of two liters ofcapacity equipped with stirrer and bubble condenser, heated in an oilbath:

920 g of n-1-perfluorooctyl iodide (molecular weight 546; 1.68 mol); and

246 g of n-alpha-eicosene (molecular weight 280; 0.878 mol).

After heating up to 85° C.,

3 g of tert.-butyl-peroxy-ethyl-hexanoate is added, with good stirring,as three portions of 1 g each at intervals of one hour.

The reaction of addition of n-1-perfluorooctyl iodide to the double bondof n-alpha-eicosene is exothermic (maximum increase in temperature about15° C.). The reaction mixture is kept at a temperature comprised withinthe range of from 85° to 100° C. for a total time of six hours. At theend of this time period, 0.6% of the initial amount of n-alpha-eicoseneis still present (determination by gas-chromatography). The excess ofperfluoro-alkyl iodide is evaporated off by heating the reaction mixtureup to 115° C. and decreasing the pressure down to 5 mm Hg.

The reaction mixture is then cooled down to 60° C. and the following areadded:

320 ml of ethanol; and

200 g of zinc powder (70-100 μm).

Subsequently,

200 ml of hydrochloric acid at 37% (weight/weight) is added in an80-minutes time and with strong stirring.

The reduction reaction is an exothermic one and the temperatureincreases up to 78°-80° C., the boiling point of ethanol-waterazeotropic mixture. One hour later than the end of the addition ofhydrochloric acid, the reaction is complete and no organic iodide ispresent any longer (gas-chromatographic determination).

With temperature being maintained at about 70° C.,

400 ml of hot toluene; and

200 ml of hot water are added.

The mixture is filtered when hot in order to remove any unreacted zinc.The lower aqueous phase is separated from the filtrate and is discarded.The organic phase is recovered. The latter is washed three times, athigh temperature, with an aqueous solution containing 5-10% by weight ofsodium chloride and 1% by weight of sodium carbonate. The solvent iscompletely removed from the organic phase by distillation under vacuum(temperature up to 130° C.; pressure up to 5 mm Hg).

The distillation residue is cooled and 600 grams is obtained of a nearlycolourless mass, a waxy solid with a melting point of 68°-72° C.,containing 0.3% by weight of olefin (gas-cromatographic analysis) andwith an iodine content of 345 ppm (parts per million parts by weight).

NMR ANALYSIS

CH3--CH2--(CH2)--CH2--CH2--RF paraffinic chain; solvent CDCl3; referencetetramethyl silane.

CH3: 0.861 ppm; multiplet; 1 C atom;

CH2--: 1.240 ppm; multiplet; 17 C atoms;

CH2--: 1.577 ppm; multiplet; 1 C atom;

CH2: 2.027 ppm; multiplet; 1 C atom;

CF3--CF2--CF2--(CF2)3--CF2--CF2--RH perfluorinated chain, solvent CDCl3;reference CFCl3.

CF3: --82.16 ppm; singlet; 1 C atom;

CF2--: --115.60 ppm; singlet; 1 C atom;

CF2--: --123.26 ppm; singlet; 3 C atoms;

CF2--: --124.10 ppm; singlet; 1 C atom;

CF2--: --124.90 ppm; singlet; 1 C atom;

CF2--: --127.52 ppm; singlet; 1 C atom.

In the following Examples 2, 3 and 4, further compounds with formula (I)according to the present invention are prepared. The method used is thesame as of Example 1 and for each example the data is reported asindicated hereunder.

For the addition reaction:

n-1-perfluoro-alkyl iodide: type and amount,

n-alpha-olefin: type and amount,

catalyst: type and amount,

temperature and reaction time;

For the reduction reaction:

zinc powder: amount,

hydrochloric acid at 37% by weight: amount.

End product: amount and characteristics.

EXAMPLE 2

Preparation of CF3--(CF2)7--CH2--CH2--(CH2)p--CH3 (average molecularweight 715; mixture of components with p=15, 17, 19 and 21).

Addition reaction:

n-1-perfluorooctyl iodide: 950 g; 1.74 mol;

n-alpha-olefin: CH2=CH--(CH2)p--CH3: 240 g; 0.82 mol; mixture of:

    ______________________________________                                        n-alpha-octadecene    1% by weight                                            n-alpha-eicosene     49% by weight                                            n-alpha-docosene     42% by weight                                            n-alpha-tetracosene   8% by weight                                            ______________________________________                                    

tert.-butyl-peroxy-ethylhexanoate: 3 g;

85° C.; 8 hours.

Reduction reaction:

zinc powder: 200 g;

hydrochloric acid at 37% by weight: 220 ml.

End product:

550 g is obtained of a solid waxy mass, slightly yellow coloured, withmelting temperature 59°-62° C., which contains 1.5% by weight ofolefins, with its composition being reacher of higher molecular weightcomponents.

EXAMPLE 3

Preparation of CF3--(CF2)7--CH2--CH2--(CH2)13--CH3 (molecular weight644).

Addition reaction:

n-1-perfluorooctyl iodide: 273 g; 0.5 mol;

n-alpha-hexadecene: 68 g; 0.3 mol;

azo-bis-isobutyronitrile: 0.8 g;

75°-80° C.; 5 hours.

Reduction reaction:

zinc powder: 60 g;

hydrochloric acid at 37% by weight: 100 ml.

End product:

180 g is obtained of a solid waxy mass, which is colourless, has amelting temperature of 49°-51° C., and contains 0.2% by weight ofolefins.

EXAMPLE 4

Preparation of CF3--(CF2)5--CH2--CH2--(CH2)13--CH3 (molecular weight544).

Addition reaction:

n-1-perfluorohexyl iodide: 300 g; 0.67 mol;

n-alpha-hexadecene: 90 g; 0.4 mol;

azo-bis-isobutyronitrile: 0.8 g;

75°-80° C.,; 5 hours.

Reduction reaction:

zinc powder: 80 g;

hydrochloric acid at 37% by weight: 100 ml.

End product:

210 g of a semisolid, colourless, waxy mass with melting temperature31°-32° C., which contains 0.12% by weight of olefin, is obtained.

EXAMPLE 5

The evaluation of the product is carried out by two ski masters,specialized in carrying out tests. Each of them has available two pairsof ski for ski competitions, perfectly equal, known under the trade name"ATOMIC". In each one of said two ski pairs, the soles of one ski pairare treated with the ski-wax "Holmenkol" SPACE-GLIDER GRAPHIT SG,available from the market, and the soles of the other pair of skis aretreated with the same ski-wax, to which 15% by weight, with reference tothe total weight of the mixture, of the product of Example 1 is added.

Environmental characteristics:

old snow of winter type, beaten with a mechanical means and then with 20high-speed skier passages;

thickness of snowcoat higher than 50 cm;

air temperature: from 0° to -2° C.;

snow temperature: from -4° to -6° C.;

relative humidity of snow surface: 78-80%.

All the descents and measurements are performed in the absence of sun.

Characteristics of the ski-run:

The ski-run is situated at the level of 1850 m above the sea-level, isperfectly straight, is 155 m long and shows a vertical height ofapproximately 50 m.

Before entering the ski-run, the skiers run along a high-slope launchingstretch, 98 m long.

Examples of descent

Each skier runs along the ski-run three times, with each of his twopairs of skis. The average time of descent is as follows:

with Holmenkol ski-wax: 7.54 seconds (t1) (average value from sixtests);

with Holmenkol ski-wax containing 15% by weight of product of Example 1:7.38 seconds (t2) (average value from six tests).

     t%=(t1-t2)/t1×100=1.59%.

The evaluation is repeated the day after. The ski soles are carefullycleaned with the cleaning agent "Toko" currently available from themarket. Both said ski pairs treated the day before with the sky-waxavailable from the market are treated with the ski-wax admixed with theproduct from Example 1, as indicated above, and the contrary is done onthe other two pairs of skis.

In this case, the temperature of snow is comprised within the range offrom -6° to -8° C. and air temperature is comprised within the range offrom -3° to -4° C., with a relative humidity of snow surface of 68-72%.Results are obtained, which are at all similar to as reported above.

EXAMPLE 6

This test is carried out in the same way as in above Example 5, usingthe following ski-waxes:

ski-wax available from the market "Briko yellow grade" (of universaltype); and

ski-wax available from the market "Briko yellow grade" (of universaltype) admixed with 20% by weight (relatively to the total weight of themixture) of the product of Example 2.

The tests are carried out under the following conditions:

air temperature: from +1° to 0° C.;

snow temperature: from -2° to -4° C.;

relative surface humidity: 80-83%.

The following descent times are measured:

with "Briko yellow grade" ski-wax: 7.49 seconds (t1) (average value fromsix tests);

with "Briko yellow grade" ski-wax containing 20% by weight of theproduct of Example 1: 728 seconds (t2) (average value from six tests);

t%=(t1-t2)/t1×100=2.8%.

EXAMPLE 7

The instant example is carried out similarly to Example 5, with twoappraisers, specialized ski masters, each having two racing ski pairs.

The characteristics of snow are: old snow, of spring type, leveled butnot very much beaten. Before the test several high-speed passages arecarried out. The ski-run is perfectly straight, is 120 m long, with ahigh initial slope and nearly horizontal in the end portion. Thelaunching stretch, with high slope, is 40 meters long.

The other conditions are:

air temperature: from -8° to -10° C.;

snow temperature: from -9° to -11° C.;

relative surface humidity: 71-73%.

The descents are carried out in the absence of sun.

A ski-wax available from the market "Swix violet" and a mixture of thelatter with 10% by weight (with reference to the weight of the mixture)of the product of Example 1 are used.

The following descent times are measured:

with "Swix violet" ski-wax: 5.97 seconds (t1) (average value from tentests);

with "Swix violet" ski-wax containing 10% by weight of product fromExample 1: 5.93 seconds (t2) (average value from 10 tests).

t%=(t1-t2)/t1×100=0.67%.

EXAMPLE 8

400 g of the product of Example 1, as microgranules with average size0.4-0.5 mm, is mixed, in a planetary mixer, with 10 kg of high-densitypolyethylene powder, a product marketed under the trade name "Lupolen"5661B (BASF).

The mixture if extruded with a screw extruder with laminar head, at 220°C. A band of 10 cm of width and 1.5 mm of thickness is obtained.

A portion of this band is polished with abrasive paper and then is keptat 60° C. in an oven for 48 hours.

ESCA analysis (Electron Spectroscopy for Chemical Analysis) of thesurface, down to a depth of about 0.2 μm, shows the presence of fluorinein a concentration of 5.3% by weight. The contact angle of the samesurface is of 111°.

A band of "Lupolen" 5661B in its pristine state, not admixed with theproduct of Example 1, prepared and treated by the same methodology,shows a contact angle of 73°.

We claim:
 1. Composition affording sliding characteristics, whichcomprises:a paraffinic wax, and a compound or mixture of compounds withformula (I):

    CF3--CnF2n--Cm--H2m--CH3                                   (I)

wherein: n is a numeral comprised within the range of from 1 to 21; m isa numeral comprised within the range of from 3 to 25; n+m is a numeralequal to, or higher than, 18; with the chain of carbon atoms beingeither linear or branched.
 2. Composition affording slidingcharacteristics according to claim 1, in which in said formula (I):n isa numeral comprised within the range of from 3 to 15; m is a numeralcomprised within the range of from 5 to 23; n+m is a numeral equal to,or higher than, 18; with the chain of carbon atoms being either linearor substantially linear.
 3. Composition affording slidingcharacteristics according to claim 2, in which said compounds withformula (I) are:CF3--(CF2)15--(CH2)15--CH3--a semi-solid, colourlessproduct with waxy appearance, with melting point 31°-32° C.;CF3--(CF2)7--(CH2)15--CH3--a solid, colourless product with waxyappearance, with melting point 49°-51° C.; CF3--(CF2)7--(CH2)19-13CH3--a solid, colourless product with waxy appearance, with meltingpoint 68°-72° C.; CF3--(CF2)7--(CH2)p--CH3--a solid, colourless productwith waxy appearance, which is a mixture of four components with p=17,19, 21 and 23, with melting point 59°-62° C.
 4. Composition affordingsliding characteristics according to claim 3, in which the content ofcompound or mixture of compounds with formula (I) is comprised withinthe range of from 0.1 to 99% by weight, relatively to the weight of thecomposition.
 5. Composition affording sliding characteristics accordingto claim 4, in which said content of compound or mixture of compoundswith formula (I) is comprised within the range of from 3 to 25% byweight, relatively to the weight of the composition.
 6. Process forendowing a ski with sliding characteristics, in which a composition asdefined in claim 1 is applied onto the sole of said ski and/or isincorporated inside the sole of said ski.
 7. Process for endowing a skiwith sliding characteristics, in which a composition as defined in claim5 is applied onto the sole of said ski and/or is incorporated inside thesole of said ski.